Retractable blade tail unit for projectiles



"A ril 7, 1964 F. MORATTI ETAL RETRACTABLE BLADE TAIL UNIT FOR Filed Sept. 18, 1961 PROJECTILES I5 Sheets-Sheet 1 April 7, 1964 F. MORATTI ETAL 3,127,838

RETRACTABLE BLADE TAIL UNIT FOR PROJECTILES Filed Sept. 18, 1961 5 Sheets-Sheet 2 INVENTORS BY MM W-M April 7, 1 F. MORATTI ETAL 3,

' RETRACTABLE BLADE TAIL UNIT FOR PROJECTILES Filed Sept. 18, 1961 3 Sheets-Sheet 5 iifiinnnv INVENTORS United States Patent 3,127,838 RETRACTABLE BLADE TAIL UNIT FGR PROJECTILES Francesco Moratti and Carlo Tosti, Qoileferro, Rome, Italy, assignors to Bombrini Parodhlltelfino ocieta per Azioni, Rome, lltal a company of Italy Filed Sept. 18, 196i, Ser. No. 138,824) Claims priority, application ltaly Oct. 12, 196i) 3 (Ilaims. (Cl. 10250) The present invention relates to a retractable blade tail unit for guiding projectiles, of either the self propelled type or non self propelled type, for any use (air to air, air to surface, surface to surface, surface to air) and of any calibre.

The use of tail units of the retractable type, the blades of which are when in closed position, located within simple geometrical shapes and capable of being inscribed within a cylinder, is preferable in many cases for the reasons as follows:

(a) Simplicity of transport and storage;

(b) Possibility of use of tubular launching devices, which are easily embodied, non expensive and which have a minimum bulk;

(0) Maximum concentration of destroying power available at parity of occupied volume;

(d) Safe handling.

The present invention aims to provide a tail unit of the concerned type having, however, with respect to the retractable blade units known up to date, certain determined advantages as will be hereinafter disclosed.

The tail unit according to the present invention which can be applied, as aforesaid, to either the self propelling projectiles or to the non self propelling type, of any use and with no limitation as to their calibre, is of the flat trapezoid shape blade type. The blades lie, in their retracted position, in planes parallel to the longitudinal axis of the projectile on which the tail unit is mounted, while in their completely opened position said blades lie in radial planes, i.e. in planes passing through the longitudinal axis of the projectile; the position of final opening of each blade is obtained by a single rotational movement, having a pre-established extent, about a pivot pin the ads of which is located in inclined position with respect to the longitudinal axis of the projectile.

Particularly, according to this invention a trapezoidal shaped retractable blade tail unit is provided comprising, in combination, a plurality of trapezoidal shaped flat blades, a bushing readily applied to the body of the projectile to which the tail unit is fixed, and means capable of causing and guiding the passage of the blades from a closed position in planes parallel to the longitudinal axis of the projectile on which the tail unit is mounted, in which position the blades are inscribed within a cylinder whose cross section is a circle determined by the calibre of the launching tube for the projectile, to an open position where said blades are lying in radial planes passing through said longitudinal axis. The passage from the closed position to the completely open position is obtained by a single rotary movement having the same extent for each blade.

Also, according to the present invention, each blade is applied to said bushing by means of a terminal block which is connected to said bushing by means of a pivot pin about which said rotation is carried out through the same extent and in the same direction, said pivot pin being located in inclined position with respect to the longitudinal axis of the projectile.

It is obvious that from the configuration of the trapezoidal shaped flat blades radially located in perfect symmetry there are several advantages with respect to other shapes of blades, either of the type tangent to a circle 7 (FIG. 6).

3,127,838 Patented Apr. 7, 1964 or of the curve type with simple or double cylindrical sectors or finally of the double hinge flat type.

In fact, with the radial fiat trapezoidal shape, the aerodynamic disturbances are practically nonexistant, and therefore the entire surfaces of the blades co-operate to stabilize the projectile.

One preferred embodiment of the tail unit according to this invention will be disclosed in the following specification with reference to the attached drawings, wherein:

FIG. 1 is a longitudinal view of the tail unit located in the terminal portion of a self propelled projectile, in the closed position of the tail unit;

PEG. 2 is a cross-sectional view along the line IIII of the tail unit of FIG. 1;

FIG. 3 is an axial sectional view of said tail unit in its open position, i.e. after the projectile has issued from the launching tube;

FIG. 4 is a front elevational View of the tail unit in its open position, taken along the line IV-IV of FIG. 3; and

FIGS. 5 and 6 are detail views showing a normal view along the line VV of FIG. 4 and a cross-sectional view taken along the line VL-VI of FIG. 5, respectively of the mounting of the blades of the tail unit, of their rotation system and of the subsequent lock.

As shown in FIG. 3, the tail unit can be mounted on the terminal portion of the nozzle 10 of a motor rocket partially shown at lit) by a threaded coupling 9.

With reference to FIGS. 1 to 6, the tail unit of the illustrative example comprises essentially:

Four blades 1 made of light alloy each having trapezoid shape, each blade having at one of its ends a contoured block 2 (FIGS. 1 and 4) where are provided one bore for receiving the threaded pin 3, an annular recess 3 concentrical with the bore for the pin 3, in said recess being received the helical spring 4, and a cone shaped bore where the locking bolt 5 can engage A blade carrying bush 6, made of light alloy, is provided with four symmetrical recesses 7 with the planes for the rest and lock of the blade carrying blocks 2. Each of the recesses 7 has a fiat surface located in a plane at right angles to an axis inclined with respect to the longitudinal axis of the body of the projectile and a rest surface located at a right angle to such longitudinal axis. In said recesses there are also provided four annular recesses where some loops of the helical springs 4 are received, and four threaded bores for receiving the pins 3, and four blind bores for receiving the locking bolts 5 and their associated springs 8. Also, the bushing 6 is provided with a threaded zone 9 for mounting the tail unit on the nozzle 10.

Summarizing the unit comprises four threaded pins 3 provided with shoulders, four helical springs 4 each of which is engaged with its ends in the annular recesses of the bushing 6 and of the terminal block 2 of the blades, respectively; four conical locking bolts 5 and four springs 8 in compressed state, acting on the conical locking bolts 5.

By way of example the operation of the tail unit will be described in the case of rocket projectiles to be used for surface to air use, and thus starting from rest.

As soon as the propellant has been ignited, the rocket instantaneously starts its forwards movement within the launching tube 11 which is shown in dotted line in FIG. 1; the blades are in their retracted position, i.e. enveloped within a cylinder having a diameter equalling the inner diameter of the launching tube 11 (FIG. 1). Further the contoured terminal block 2 of each blade covers by its flat portion resting on the bushing, the associated locking bolt 5; the latter is thereby completely retracted within its recess and compresses almost completely the spring 8.

As soon as the rocket has left the tubular guide of the launching tube 11, the blades 1 rotate about the pivot pins 3, under the action of the torque generated by the springs 4. Also, in this specific case, the opening of the blades is favourably influenced by both the inertia force acting on the rocket in its propelled stage and the air drag; these forces create positive tilting moments in the direction of the opening movements of the blades.

Therefore, the blades rotating through a certain angle about the pivot pins 3, move from their closed positions to their radial positions and will be locked at the latter positions, resting on the four rest planes provided on the bushing 6.

Simultaneously, at the end of their rotational movements the four blades are engaged by the locking bolts 5 which are pushed by the compressed springs 8, and enter the associated conical bores provided in the terminal blocks 2. Thus the four blades are perfectly locked to the bushing 6 and any return movement of the blades towards their initial closed position will be prevented.

The rotational movement of the blades about the pivot pins could be generated, besides by the spring unit as described in the above disclosed example, even by means of other forces, for instance a single spring controlling a central bushing acting on eccentric pins provided in the blades, or, in the case of the rockets, by a single central bushing operated by the inertia forces in the self-propelled stage, said bushing acting on the blades by means of eccentric pins also in this case; or the tilting moments could be obtained by forces either of inertia or aerodynamic acting on the single blades, and so on.

While in the described example the tail unit comprises four retractable blades, the number of the blades can be also different, provided that the enveloping and symmetry conditions Will be maintained.

The present invention has been illustrated and described in one preferred embodiment, but it is intended that constructive variations could be practically adopted without departing from the scope of the following claims.

We claim:

1. A projectile comprising a body, a tail unit arranged on the end portion of said body comprising a bushing threadedly secured to said body having a plurality of recesses at its side adjacent said body, a plurality of trapezoidal stabilizing fins, each of said recesses having a flat surface located in a plane at a right angle to an axis inclined with respect to the longitudinal axis of said body and a rest surface located at a right angle to said longitudinal axis, a pivot in each recess secured to said bushing for pivoting said fins, each root end of said fins having a bore through which said pin passes, said bores being aligned in inclined position with respect to the longitudinal axis of said projectile body, said root ends having a first surface capable of sliding on said flat surface to rotate about said pivot pin and a second surface normal to said first surface for resting on said rest surface when said fins are in extended position and a plurality of helical springs cooperating with said bushing and root ends urging said fins from a position parallel to the longitudinal axis of said projectile body to a position wherein said fins lie in a plane at right angles to said longitudinal axis of said body.

2. A projectile comprising a body, a tail unit arranged on the end portion of said body comprising a bushing threadedly secured to said body having a plurality of re cesses at its side adjacent said body, a plurality of trapezoidal stabilizing fins, each of said recesses having a fiat surface located in a plane at a right angle to an axis inclined with respect to the longitudinal axis of said body and a rest surface located at a right angle to said longitudinal axis, a pivot in each recess secured to said bushing for pivoting saidfins, each root end of said fins having a bore through which said pin passes, said bores being aligned in inclined position with respect to the longitudinal axis of said projectile body, said root ends having a first surface capable of sliding on said flat surface to rotate about said pivot pin and a second surface normal to said first surface for resting on said rest surface when said fins are in extended position, a plurality of helical springs cooperating'with said bushing and root ends urging said fins from a position parallel to the longitudinal axis of said projectile body to a position wherein said fins lie in a plane at right angles to said longitudinal axis of said body and means for locking said fins in said last named position.

3. A projectile as claimed in claim 2, wherein each root end is provided with a cone shaped opening, said bushing has in each recess a hole extending parallel to said pin, spring means arranged in each hole, a bolt having a cylindrical portion located in each hole and a cone shaped end, said cylindrical portion resting on said spring means and said cone shaped end engaging said cone shaped opening in the extended position of said fins.

References Cited in the file of this patent UNITED STATES PATENTS 1,879,840 Brandt Sept. 27, 1932 2,700,337 Cumming Jan. 25, 1955 3,031,967 Jasse May 1, 1962 3,063,375 Hawley et al. Nov. 13, 1962 FOREIGN PATENTS 1,187,193 France Sept. 8, 1959 

1. A PROJECTILE COMPRISING A BODY, A TAIL UNIT ARRANGED ON THE END PORTION OF SAID BODY COMPRISING A BUSHING THREADEDLY SECURED TO SAID BODY HAVING A PLURALITY OF RECESSES AT ITS SIDE ADJACENT SAID BODY, A PLURALITY OF TAPEZOIDAL STABILIZING FINS, EACH OF SAID RECESSES HAVING A FLAT SURFACE LOCATED IN A PLANE AT A RIGHT ANGLE TO AN AXIS INCLINED WITH RESPECT TO THE LONGITUDINAL AXIS OF SAID BODY AND A REST SURFACE LOCATED AT A RIGHT ANGLE TO SAID LONGITUDINAL AXIS, A PIVOT IN EACH RECESS SECURED TO SAID BUSHING FOR PIVOTING SAID FINS, EACH ROOT END OF SAID FINS HAVING A BORE THROUGH WHICH SAID PIN PASSES, SAID BORES BEING ALIGNED IN INCLINED POSITION WITH RESPECT TO THE LONGITUDINAL AXIS OF SAID PROJECTILE BODY, SAID ROOT ENDS HAVING A FIRST SURFACE CAPABLE OF SLIDING ON SAID FLAT SURFACE TO ROTATE ABOUT SAID PIVOT PIN AND A SECOND SURFACE NORMAL TO SAID FIRST SURFACE FOR RESTING ON SAID SURFACE WHEN SAID FINS ARE IN EXTENDED POSITION AND A PLURALITY OF HELICAL SPRINGS COOPERATING WITH SAID BUSHING AND ROOT ENDS URGING SAID FINS FROM A POSITION PARALLEL TO THE LONGITUDINAL AXIS OF SAID PROJECTILE BODY TO A POSITION WHEREIN SAID FINS LIE IN A PLANE AT RIGHT ANGLES TO SAID LONGITUDINAL AXIS OF SAID BODY. 